Buggy code:
public class ConstraintFactory { private final MachineModel machineModel ; private final LogManagerWithoutDuplicates logger ; private final String functionName ; private final Optional < ValueAnalysisState > valueState ; private SymbolicValueFactory expressionFactory ; private ConstraintFactory ( String pFunctionName , Optional < ValueAnalysisState > pValueState , MachineModel pMachineModel , LogManagerWithoutDuplicates pLogger ) { } public static ConstraintFactory getInstance ( String pFunctionName , Optional < ValueAnalysisState > pValueState , MachineModel pMachineModel , LogManagerWithoutDuplicates pLogger ) { } public Constraint createNegativeConstraint ( CBinaryExpression pExpression ) throws UnrecognizedCodeException { } public Constraint createNegativeConstraint ( JUnaryExpression pExpression ) throws UnrecognizedCodeException { <START_BUG> Constraint positiveConstraint = createNot ( createPositiveConstraint ( pExpression ) ) ; <END_BUG> if ( positiveConstraint == null ) { return null ; } else { return createNot ( positiveConstraint ) ; } } public Constraint createNegativeConstraint ( JBinaryExpression pExpression ) throws UnrecognizedCodeException { } public Constraint createNegativeConstraint ( AIdExpression pExpression ) throws UnrecognizedCodeException { } public Constraint createPositiveConstraint ( CUnaryExpression pExpression ) throws UnrecognizedCodeException { } public Constraint createPositiveConstraint ( CBinaryExpression pExpression ) throws UnrecognizedCodeException { } private boolean isConstraint ( CBinaryExpression pExpression ) { } public Constraint createPositiveConstraint ( JUnaryExpression pExpression ) throws UnrecognizedCodeException { } public Constraint createPositiveConstraint ( JBinaryExpression pExpression ) throws UnrecognizedCodeException { } private boolean isConstraint ( JBinaryExpression pExpression ) { } public Constraint createPositiveConstraint ( AIdExpression pExpression ) throws UnrecognizedCodeException { } private Constraint transformValueToConstraint ( SymbolicExpression pExpression , Type expressionType ) { } private JExpressionTransformer getJavaTransformer ( ) { } private CExpressionTransformer getCTransformer ( ) { } private boolean isNumeric ( Type pType ) { } private boolean isBoolean ( Type pType ) { } private SymbolicExpression getOneConstant ( Type pType ) { } private SymbolicExpression getTrueValueConstant ( ) { } private Type getCalculationType ( Type pType ) { } private Type getCCalculationType ( CType pType ) { } private Type getJCalculationType ( JType pType ) { } private UnaryConstraint createNot ( Constraint pConstraint ) { } private UnaryConstraint createNot ( SymbolicExpression pSymbolicExpression ) { } private Constraint createLess ( SymbolicExpression pLeftOperand , SymbolicExpression pRightOperand , Type pExpressionType , Type pCalculationType ) { } private Constraint createLessOrEqual ( SymbolicExpression pLeftOperand , SymbolicExpression pRightOperand , Type pExpressionType , Type pCalculationType ) { } private Constraint createNotEqual ( SymbolicExpression pLeftOperand , SymbolicExpression pRightOperand , Type pExpressionType , Type pCalculationType ) { } private Constraint createEqual ( SymbolicExpression pLeftOperand , SymbolicExpression pRightOperand , Type pExpressionType , Type pCalculationType ) { } }

Fix:
Constraint positiveConstraint = createPositiveConstraint ( pExpression ) ;